I think it disappeared because the event is over (was available until 23 March), but another one will come soon and there will definitely be a new climb.
Probably the server was unable to record your game progress and now you will need to improve the level. This can be very frustrating, next time try waiting a little longer before closing the app.
Hi! To pass this level you have to try to accumulate 15 pieces of chocolate. You have to be careful not to break it right away, try to always leave a few squares so that it can regenerate up to 15.π